Method of washing and drying substrates

ABSTRACT

A method for washing and drying a substrate and an apparatus therefor are disclosed which are capable of effectively rapidly carrying out the washing and drying of a semiconductor substrate in good yields without damaging and contaminating the substrate. The method comprises the steps of immersing a carrier carrying at least one substrate thereon into wash liquid; drawing up the carrier from the wash liquid while oscillating the substrate; and feeding drying gas to the substrate during the drawing-up of the carrier to remove the wash liquid from the surface of the substrate. The apparatus of the invention is constructed to allow the method to be effectively practiced.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a method for washing and drying a substrateand an apparatus therefor, and more particularly to a method for washingand drying a substrate used for the production of a semiconductor devicesuch as, for example, a silicon wafer, glass mask or the like and anapparatus suitable for practicing such a method.

2. Description of the Prior Art

Conventionally, the washing and drying of a semiconductor wafer whichhas been subjected to processing and a chemical treatment is carried outin a manner to put the semiconductor wafer carried on a carrier orretainer in a high speed rotating unit to wash the semiconductor waferand dry it utilizing centrifugal force generated by the rotating unit.However, such a conventional method unfortunately causes the generationof dust from a revolving shaft of the rotating unit, which adheres tothe semiconductor wafer during the rotation of the unit. Theconventional method has another problem that semiconductor wafersadjacent to each other are contacted therebetween during the rotation ofthe unit to cause chipping of the semiconductor wafers. Further, suchchipping leads to the contamination of adjacent semiconductor wafers dueto adhesion of the chips thereto. Thus, it will be noted that theconventional method has an important disadvantage of failing to carryout the washing and drying of a semiconductor wafer in good yields.Accordingly, it would be highly desirable to provide a method forrapidly carrying out the washing and drying of a substrate in goodyields while keeping the substrate clean during the operation.

SUMMARY OF THE INVENTION

The present invention has been made in view of the foregoingdisadvantage of the prior art.

Accordingly, it is an object of the present invention to provide amethod of washing and drying a substrate which is capable of rapidlydrying a substrate for a short period of time as well as positivelyremoving wash liquid adhering to the substrate therfrom.

It is another object of the present invention to provide a method forwashing and drying a substrate which is capable of effectivelypreventing damage of substrates due to the contact therebetween duringthe washing and drying operation, to thereby accomplish the operation ingood yields.

It is a further object of the present invention to provide an apparatusfor washing and drying a substrate which is capable of positivelyremoving wash liquid from the substrate and effectively preventing thegeneration of dust and the chipping of the substrate during the washingand drying operation, to thereby accomplish the operation in highyields.

In accordance with one aspect of the present invention, there isprovided a method for washing and drying a substrate comprising thesteps of immersing a carrier carrying at least one substrate thereoninto wash liquid; drawing up the carrier from the wash liquid whileoscillating the substrate; and feeding drying gas to the substrateduring the drawing-up of the carrier to remove the wash liquid from thesurface of the substrate.

In a preferred embodiment of the present invention, the carrier is drawnup at a speed of 1.5-4.2 cm/min.

In accordance with another aspect of the present invention, there isprovided an apparatus for washing and drying a substrate comprising amovable base arranged to be vertically movable along guide means; acarrier for receiving at least one substrate therein; clamping meansarranged on the movable base to clamp the carrier; oscillating meansarranged on the movable base to oscillate the substrate; a wash liquidvessel in which the carrier is immersed; and means for feeding dryinggas to the substrate received in the carrier during the drawing-up ofthe carrier from the vessel while being oscillated.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and many of the attendant advantages of thepresent invention will be readily appreciated as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings; wherein:

FIG. 1 is a side elevation view showing one example of the manner of useof an apparatus for washing and drying a substrate according to thepresent invention and an embodiment of an apparatus according to thepresent invention;

FIG. 2 is a front elevation view showing the essential part of theapparatus shown in FIG. 1;

FIG. 3 is a front elevation view of the apparatus shown in FIG. 1wherein an intermediate movable base is upward moved;

FIG. 4 is an exploded perspective view showing clamping means andoscillating means used in the apparatus shown in FIG. 1;

FIG. 5 is a sectional view showing a modification of a plate memberconstituting a part of oscillating means in the apparatus shown in FIG.1; and

FIG. 6 is a schematic sectional view showing a state of drying the platemember shown in FIG. 5 while contacting it with a semiconductorsubstrate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, the present invention will be described hereinafter with referenceto the accompanying drawings.

FIGS. 1 to 3 shows an embodiment of an apparatus for washing and dryinga substrate according to the present invention wherein an apparatus ofthe present invention is generally designated by reference numeral 1.The apparatus 1 of the illustrated embodiment includes a lower fixedbase 2, four studs 3, 4 and 5 (the other one being not shown) each fixedat the lower end thereof on the lower fixed base 2 and upward extendingtherefrom, and an upper fixed base 7 fixedly supported on the upper endsof the studs. The apparatus 1 of the illustrated embodiment alsoincludes an intermediate movable base 8 arranged between the lower fixedbase 2 and the upper fixed base 7 so as to be vertically moved along thestuds by a predetermined distance L.

The intermediate movable base 8 is provided on the central portionthereof with a rack 9 of a round bar shape, which upward extendstherefrom. The rack 9 is operatedly engaged with a pinion 10 driven by amotor 40 disposed on the upper base 7 to vertically move theintermediate movable base 8. The intermediate movable base 8 is providedon the front side portion thereof with clamping means 11 and oscillatingmeans 15 which are constructed in such a manner as shown in FIG. 4. Theclamping means 11 is adapted to move or transfer a carrier 21 whileclamping the carrier 21 which serves to carry at least one semiconductorsubstrate 20 thereon, and the oscillating means 15 is adapted tosomewhat oscillate the semiconductor substrate 20 in the X--X directionand the Z--Z direction, as shown in FIG. 4. In the illustratedembodiment, the carrier received a plurality of the substrates 20therein.

The clamping means 11 comprises a pair of L-shaped clamping rods 12(FIG. 4) adapted to clamp the carrier 21 between the distal endsthereof, an actuator or actuating unit 13 for openably actuating theclamping rods 12 and a pair of mounting plates 14 by which the upperends of the clamping rods 12 are securely supported.

In the clamping means 11 constructed as described above, the mountingplates 14 are moved in the Y--Y direction by the actuating unit 13 toselectively adjust the interval between a pair of the clamping rods 12as desired, so that the interval therebetween may be varied dependingupon the carrier 21 used.

The oscillating means 15, as shown in FIGS. 1 and 4, comprises anoscillating rod 16 arranged at an intermediate position between theclamping rods 12 and 12 so as to be horizontal therewith, a firstdriving unit 17 for applying oscillating force to the oscillating rod 16in the X--X direction in FIG. 1 and a second driving unit 18 for movingthe oscillating rod 16 in the Z--Z direction. In the illustratedembodiment, the oscillating rod 16 is bent into substantially aninverted U-shape and has a plate member 19 of an inverted T-shape insection mounted on the free end thereof.

The oscillating means 15 constructed as described above is operated in amanner such that the second driving unit 18 is actuated to abut theplate member 19 of the oscillating rod 16 against the lower end of thesemiconductor substrate 20 carried on or received in the carrier 21clamped between the clamping rods 12 and 12, and then the first drivingunit 17 is actuated to oscillate the oscillating rod 16 in the X--Xdirection, to thereby allow the carrier 21 to be somewhat oscillated inthe X--X direction.

In FIG. 1, reference numerals 30, 31, 32 and 33 designate a means forfeeding drying gas such as clean dried air, a blower, a filter and aheater, respectively.

Now, the manner of operation of the apparatus of the illustratedembodiment as described above will be described hereinafter withreference to FIGS. 1 to 3.

First, the intermediate movable base 8 of the apparatus 1 is positionedat the position shown in FIG. 3 and the actuating unit or actuator 13 isactuated to adjust the interval between the clamping rods 12 and 12depending upon the width of the carrier 21 used, as shown in FIG. 3.Then, the clamping rods 12 are actuated to clamp the carrier 21therebetween through flanges formed at the upper edges of both sidewalls of the carrier 21 and then the second driving unit 18 is actuatedto move the oscillating means 15 in the Z--Z direction, to thereby abutthe plate member 19 against the lower end of each of the semiconductorsubstrates 20. Thereafter, the motor 40 mounted on the upper fixed base7 is driven to lower the carrier 21 into a wash liquid vessel 25 tofully immerse the substrate 20 in wash or cleaning liquid. Subsequently,the plate member 19 abutted against each of the semiconductor substrates20 is oscillated, for example, in a manner such that it is reciprocatedat a distance of 2 mm every two seconds, to thereby cause the each ofsemiconductor substrates 20 to be somewhat reciorocated in the X--Xdirection. Then, the carrier 21 is drawn up from the wash or cleaningliquid at a speed as low as about 1 cm/min while providing thesemiconductor substrates 20 with such movement and concurrently thesemiconductor substrates are exposed to a stream of drying gas such asair during the drawing-up of the carrier to remove the wash liquidtherefrom. The washing and drying operation is completed when thecarrier is returned to the position shown in FIG. 3. The wash liquidcollected between the carrier 21 and the semiconductor substrates 20 iseffectively removed due to the drop from the carrier 21 during theoscillation of the semiconductor substrates 20 at a low speed in theX--X direction.

FIG. 5 illustrates a modification of the plate member constituting apart of the oscillating means 15. A plate member of the illustratedmodification generally designated by reference numeral 50 has a groove54 formed on the surface 52 thereof contacted with semiconductorsubstrates so as to extend in the longitudinal direction thereof. Thegroove 54 is formed to be communicated with a cavity 56 formed in theinterior of the plate member 50.

The plate member 50 constructed above is used in such a manner as shownin FIG. 6. More particularly, the plate member 50 is kept contacted atthe upper surface thereof with the lower surface of each ofsemiconductor substrates 20 during the washing and drying operation.After the washing operation, when the semiconductor substrates are drawnup from wash or cleaning liquid 58 while oscillating the plate member50, wash liquid remaining on the lower surface of the substrate 20 issucked through the groove 54 into the cavity 56 due to capillaryphenomenon. Thus, it will be noted that the plate member substantiallypromotes the drying of the washed semiconductor substrates 20.

As can be seen from the foregoing, the present invention is capable ofrapidly drying semiconductor substrates for a short period of timebecause it allows the surface tension of wash liquid to be available forthe drying. Also, the present invention effectively prevent thegeneration of any dust during the washing and drying operation, so thatsemiconductor substrates are kept clean. Further, the present inventionpositively prevents the chipping of semiconductor substrates to carryout the washing and drying of the semiconductors in high yields, thus, asemiconductor device such as an integrated circuit and the like are keptat a high quality.

It will thus be seen that the objects set forth above, and those madeapparent from the preceding description, are efficiently attained and,since certain changes may be made in the above construction withoutdeparting from the spirit and scope of the invention, it is intendedthat all matter contained in the above description or shown in theaccompanying drawings shall be interpreted as illustrative and not in alimiting sense.

What is claimed is:
 1. A method for washing and drying substrates,comprising the steps of:immersing a carrier for carrying substratestherein into washing liquid, the substrates being substantiallyhorizontally aligned in upright positions and each substrate havingupper and lower surface regions; drawing up the carrier carrying thesubstrates in a substantially vertical direction from the washingliquid; oscillating the substrates in a substantially horizontaldirection by contacting the lower surface regions of the substrates withoscillating means during the drawing up of the carrier; and feedingdrying gas to the substrates during the drawing up of the carrier, toremove the washing liquid from the substrates.
 2. The method of claim 1,comprising the additional step ofdrawing off the washing liquid from thelower surface regions of the substrates through a groove provided in theoscillating means, and into a cavity in the oscillating means andcommunicating with the groove.
 3. The method of claim 2, wherein thestep of drawing up the carrier, is carried out at a speed of about1.5-4.2 cm/min.
 4. A method for washing and drying substrates,comprising the steps of:immersing a carrier for carrying substratestherein into washing liquid, the substrates being substantiallyhorizontally aligned in upright positions and each substrate havingupper and lower surface regions; drawing up the carrier carrying thesubstrates in a substantially vertical direction from the washing liquidat a speed of between about 1.5-4.2 cm/min.; oscillating the substratesin a substantially horizontal direction by contacting the lower surfaceregions of the substrates with oscillating means during the drawing upof the carrier; and feeding drying gas to the substrates during thedrawing up of the carrier, to remove the washing liquid from thesubstrates.
 5. A method for washing and drying substrates,comprising:immersing a carrier for carrying substrates therein intowashing liquid; removing the carrier for carrying the substrates fromthe washing liquid; oscillating the substrates in a substantiallyperpendicular direction to a direction of the removing of the carrier,by contacting the substrates with oscillating means during the removingof the carrier; and feeding drying gas to the substrates during theremoving of the carrier, to remove the washing liquid from thesubstrates.
 6. The method of claim 5, wherein the oscillating meanscontact each of the substrates.
 7. The method of claim 5, comprising theadditional steps ofdisposing the substrates upon the carrier; clampingthe carrier to a movable support; and moving the oscillating means tocontact a lower surface of each substrate, prior to immersing thecarrier in the washing liquid, whereby the carrier is immersed andremoved by moving the movable support.
 8. The method of claim 5, whereinthe carrier is removed from the washing liquid at a speed down to about1 cm/min.
 9. The method of claim 5, comprising the additional stepofreciprocating the oscillating means at a distance of about 2 mm. aboutevery two seconds.